Guide catheter

ABSTRACT

A guide catheter includes a hollow elongate shaft defining a channel. The hollow elongate shaft (or a segment thereof) includes an inner tube and a multilayer sheath formed around the inner tube. The multilayer sheath includes an intermediate layer derived from a melt-processible first polyether-block amide material (e.g., PEBAX®) and an outer layer derived from a different second polyether-block amide (e.g. a cross-linked polyether-block amide material). Reinforcing material (such as a braid of reinforcing filament) may be part of the multilayer sheath. The second polyether-block amide layer of the outer layer provides a shrink tube with a shrink temperature range greater than melt temperature range of the first polyether-block amide material of the intermediate layer. The hollow elongate shaft is formed by heating the intermediate and outer layers at a temperature within the shrink temperature range such that the outer shrink tube layer shrinks and the intermediate layer melts to thereby bond the multilayer sheath to the inner tube.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates broadly to catheters. More particularly, thisinvention relates to guide catheters for introducing medical devicesand/or therapeutic agents into a body of a patient.

2. State of the Art

Guide catheters are used in surgical applications to provide apassageway through which medical devices and/or therapeutic agents maybe introduced within the body of a patient. In intravascular andcoronary applications, such medical devices typically include balloondilation catheters, guide wires or other therapeutic devices and thetherapeutic agents typically include contrast media or other therapeuticfluids.

A guide catheter includes a follow shaft defining an inner channelthrough which the medical devices or agents are delivered once the shafthas been inserted into the body. The inner channel typically comprises alubricous material such as polytetrafluoroethylene (PTFE), commonlyknown as TEFLON®, together with a metal braid surround and a flexibledurable outer sheath. The outer sheath is typically formed from apolyether-block amide material marketed under the trademark PEBAX® whichis commercially available from Atofina Chemicals Inc. of King ofPrussia, Pa.

The shaft is typically manufactured by placing fluorinatedethylene-propylene (FEP) shrink tubing over an assembly that includes amandrel with the PTFE inner channel, the metal braid surround, and thePEBAX® outer sheath. The assembly is heated to activate the FEP shrinktubing and melt the PEBAX® outer sheath. The FEP shrink tubing is thenremoved and discarded, and the mandrel is removed leaving the elongateshaft. The use of such FEP shrink tubing adds significant material coststo the guide catheter. Moreover, the labor and tooling required toremove the FEP shrink tubing adds significant manufacturing costs to theguide catheter.

Thus, there remains a need in the art to provide a guide catheter withlower material and manufacturing costs. The present invention fulfillsthese and other needs, and addresses other deficiencies of the prior artimplementations and techniques.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a guide catheterthat avoids the high material costs of FEP shrink tubing.

It is another object of the invention to provide a guide catheter thatavoids the manufacturing costs of the process steps and tooling requiredto remove FEP shrink tubing.

It is a further object of the invention to provide a guide catheter thanis suitable for a wide variety of applications, including intravascularand coronary applications.

It is also an object of the invention to provide a guide catheter thatenables positioning, guiding and use in conjunction with fluoroscopicand/or ultrasonic imaging techniques.

In accord with these objects, which will be discussed in detail below,an improved guide catheter includes a hollow elongate shaft defining achannel adapted to pass medical devices and/or therapeutic agentstherethrough. The hollow elongate shaft (or hollow elongate shaftsection) includes an inner tube and a multilayer sheath formed on theouter surface of the inner tube. The multilayer sheath includes anintermediate layer derived from a first polyether-block amide material(e.g., PEBAX®) and an outer layer derived from a differentpolyether-block amide (e.g. a cross-linked polyether-block amidematerial). Reinforcing material (such as a braid of reinforcingfilament) may also be part of the multilayer sheath. Preferably, thesecond polyether-block amide layer of the outer layer provides a shrinktube with a shrink temperature greater than a glass transitiontemperature for the first polyether-block amide material of theintermediate layer. In this configuration, the shaft is formed byheating the intermediate layer and outer layer at the shrink temperaturesuch that the outer shrink layer shrinks and the intermediate layermelts to thereby bond the multilayer sheath to the inner tube. The outershrink tube layer remains as part of the elongate shaft. The inner tubeis preferably formed from a lubricous polymeric material such as PTFE orthe like.

It will be appreciated that the improved guide catheter of the presentinvention avoids the high material costs of FEP shrink tubing (or othershrink tubing type) as well as the manufacturing costs of the processsteps and tooling required to remove FEP shrink tubing (or other shrinktubing type).

According to one embodiment of the invention, the reinforcing materialmay include a material that is radio-opaque and/or ecogenic tofacilitate positioning, guiding and use in conjunction with fluoroscopicand/or ultrasonic imaging techniques.

Additional objects and advantages of the invention will become apparentto those skilled in the art upon reference to the detailed descriptiontaken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a guide catheter.

FIG. 2 is a cross-sectional view of the hollow elongate shaft of theguide catheter of FIG. 1 in accordance with the present invention.

FIG. 3 is a perspective view of a multi-segmented guide catheter shaftin accordance with the present invention.

FIG. 4 is a plan view of a reduced diameter distal tip suitable for useas part of the guide catheter of FIG. 1.

FIG. 5 is a plan view of a guide catheter shaft with a curved contour atits distal end in accordance with the present invention.

FIG. 6 is a plan view of a guide catheter shaft with a hooked contour atits distal end in accordance with the present invention.

FIG. 7 is a plan view of a guide catheter shaft with a compound-curvedcontour at its distal end in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, the term “melt-processible” means that the giventhermoplastic material is processible into final shapes by methodsemploying heat, such as extrusion, injection molding, hot compressionmolding, or other means. The term “melt temperature” and “melttemperature range” refers to a temperature and temperature range,respectively, of the heat that is applied to a melt-processiblethermoplastic material in processing the material into its finals shape.Finally, the term “shrink temperature” and “shrink temperature range”refers to a temperature and temperature range, respectively, of the heatthat is applied to a shrinkable thermoplastic material in processing thematerial to activate the material (i.e., make it shrink)

Turning now to FIG. 1, there is shown a perspective view of a guidecatheter 10 including a proximal end 12, distal end 14, and a hollowelongate shaft 16 extending between the proximal end 12 and the distalend 14. The hollow elongate shaft 16 defines a channel 20 (not shown inFIG. 1) through which medical devices and/or therapeutic agents may beintroduced within the body of a patient. In intravascular and coronaryapplications, such medical devices typically include balloon dilationcatheters, guide wires or other therapeutic devices and the therapeuticagents typically include contrast media or other therapeutic fluids.

A fitting (or hub) 18 and possibly a handle 19 may be coupled to theproximal end 12 as shown. The elongate shaft 16 may be formed from aunitary segment, or from multiple segments (for example the segments16A, 16B, 16C, 16D, 16E, 16F as shown in FIG. 3) that are joinedtogether as is well known. Such multiple segments may have varyingflexion characteristics if desired. The elongate shaft 16 may be formedto provide a straight shape or bent shape depending on the desiredapplication. The elongate shaft 16 may have a reduced diameter distaltip 31 at the distal end as shown in FIG. 4 and described in U.S. patentapp. No. 2004/0073158, incorporated by reference herein in its entirety.The reduced diameter distal tip 31 facilitates cannulation of a vessel.

FIG. 2 is a cross-sectional side view of the hollow elongate shaft 16 ofFIG. 1 (or hollow elongate shaft segment of FIG. 3) in accordance withthe present invention. The channel 20 is defined by the lumen of aninner tube 22, which is formed from a synthetic polymeric material.Preferably, the synthetic polymeric material is lubricious, such asPTFE, polyethylene, or the like, to facilitate passage of devices and/oragents through the channel 20 formed by the inner tube 22. A multilayersheath 23 is formed about the outer surface of the inner tube 22. Themultilayer sheath 23 includes reinforcing material 24, an intermediatelayer 26 formed from a melt-processible polyether-block amide material(e.g., PEBAX®) and an outer layer 28 formed from a differentpolyether-block amide material. Preferably, the polyether-block amidelayer of the outer layer 28 provides a shrink tube with a shrinktemperature range greater than the melt temperature range of thepolyether-block amide material of the intermediate layer 26. In thisconfiguration, the elongate shaft is formed by heating the intermediatelayer 26 and outer layer 28 within the shrink temperature range suchthat the outer layer shrinks and the intermediate layer melts to therebybond the multilayer sheath to the inner tube as described below. Theouter layer 28 preferably has a hardness that is substantially similarto the hardness of the intermediate layer 26. In addition, themelt-processible polyether-block amide material of the outer layer 28 ispreferably cross-linked and may be formed by processing the same (orsimilar) polyether-block amide material of the intermediate layer 26with ultra-violet radiation or other suitable techniques.

The reinforcing material 24 may be formed by braiding reinforcingfilaments about the outer surface of the inner tube 22 as is well known.In this configuration, the reinforcing material is typically not acontinuous layer about the outer surface of the inner tube as shown, butis wound about the outer surface in a mesh pattern leaving openings tothe outer surface of the inner tube. Such reinforcing filaments may be avariety of metallic materials (such as steel), or plastic materials(such as polyester). In addition, radio-opaque material (such asplatinum, iridium, gold, tantalum, tungsten carbide and the like) may beused to form the filaments to facilitate fluoroscopic imagingtechniques. Echogenic material (such as a composite material of jetmilled tungsten carbide and polymeric material as described in U.S.patent app. No. 2004/0073158) may also be used to form the filaments tofacilitate guiding of the catheter utilizing ultrasonic imagingtechniques. In addition, material that is both radio-opaque andechogenic (e.g., a polymer, such as PEBAX®, together with an appropriateradio-opaque and echogenic filler, such as tungsten carbide particles),may be used to form the filaments of the reinforcing braid.

Similarly, the polyether-block amide layer 26 and/or the polyether-blockamide layer 28 may have a radio-opaque filler material (such asplatinum, iridium, gold, tantalum, tungsten carbide and the like), anechogenic filler material (such as a composite material of jet milledtungsten carbide and polymeric material as described in U.S. patent app.No. 2004/0073158), or a material that is both radio-opaque and echogenicto facilitate guiding of the catheter utilizing fluoroscopic imagingtechniques and/or ultrasonic imaging techniques.

Preferably, the elongate shaft 16 of the guide catheter 10 is formed asfollows. First, the inner tube 22 is formed by coating a mandrel with asynthetic polymeric material and then extruding the coated mandrelthrough a die. As set forth above, the synthetic polymeric material ispreferably lubricous, such as a PTFE, polyethylene or the like, tofacilitate passage of devices through the channel 20 formed by the innertube 22. Preferably, the mandrel has a diameter of at least 3 Frenchsuch that the lumen of the inner tube 22 (which is formed when themandrel is removed) has a corresponding size. Such sizes are suitable toallow introduction of a broad array of medical devices used in modernintravascular and coronary applications. For example, an inner tube thatprovides a 3 French lumen provides the necessary clearance for guiding acatheter device having a 1 French outer diameter. Note however that thesize of the lumen of the inner tube 22 may be readily changed (increasedor decreased) for the desired application(s).

Reinforcing material 24 is then formed about the outer surface of theinner tube 22. Preferably, the reinforcing material 24 is formed bybraiding reinforcing filaments about the outer surface. In thisconfiguration, the filaments are wound about the outer surface in a meshpattern leaving openings to the outer surface of the inner tube 22. Thefilaments may be a variety of metallic materials (such as steel), orplastic materials (such as polyester). In addition, radio-opaquematerial (such as platinum, iridium, gold, tantalum, tungsten carbideand the like) may be used to form the filaments to facilitatefluoroscopic imaging techniques. Echo-visible material (such as acomposite material of jet milled tungsten carbide and polymeric materialas described in U.S. patent app. No. 2004/0073158) may also be used toform the filaments to facilitate ultrasonic imaging techniques. Inaddition, material that is both radio-opaque and echogenic (e.g., apolymer, such as PEBAX®, together with an appropriate radio-opaque andechogenic filler, such as tungsten carbide particles), may be used toform the filaments of the reinforcing braid.

The inner tube 22 with the reinforcing material 24 applied thereto iscoated with a polyether-block amide material and then extruded through adie to form a sheath 26. Examples of suitable polyether-block amidematerials are marketed under the trademark PEBAX® and commerciallyavailable from Atofina Chemicals Inc. of King of Prussia, Pa. Moreparticularly, PEBAX® is a trade name for a family of melt-processiblepolyether-block amide materials that have good hydrolytic stability andare available in a broad range of stiffnesses. In addition, PEBAX®accepts various colors and fillers (including radio-opaque and/orechogenic fillers. PEBAX® has a melt temperature range between 335° F.and 400° F.

Shrnk tubing 28 formed from a different polyether-block amide materialis placed over the assembly (e.g., covering the intermediate sheath 26).The polyether-block amide material of the shrink tubing 28 has a shrinktemperature range above the melt temperature range for the intermediatesheath material. An example of suitable material for use in the shrinktubing 28 is a cross-linked polyether-block amide material, which isfound in the shrink tubing marketed under the trademark PALLADIUM PEBAX®HEAT SHRINK TUBING and commercially available from Cobalt Polymers ofColverdale, Calif. This shrink tubing has a shrink temperature rangebetween 340° F. and 600° F. At the higher end of this temperature range,the heat must be applied for a short period of time to avoid degradationof the shrink tubing.

The resulting assembly is heated at a temperature within the shrinktemperature range of the tubing 28 (for example, at a temperature of340° F. for the PALLADIUM PEBAX® HEAT SHRINK TUBING. This activates theshrink tube layer 28 (i.e., it shrinks) and the material of theintermediate sheath 26 melts. As the shrink tube layer 28 shrinks, itforces the molten material of the intermediate sheath 26 around thereinforcing material 24 and through the openings formed by the braidstructure to contact the inner tube 22, thereby bonding the multilayersheath structure to the inner tube structure. Note that the shrinktubing layer 28 remains as part of the final shaft assembly.

The mandrel is then removed from the assembly to form the elongate shaft16. This is preferably accomplished by pulling on the mandrel wherebythe lubricious nature of the inner tube 22 allows the inner tube 22 tobe easily separated from the elongate shaft structure.

The profile and length of the elongate shaft of the guide catheterdescribed herein may be optimized for the intended method of access. Forexample, the contour of the hollow elongate shaft may be bent to form acurve, hook or compound curve as shown in FIGS. 5, 6, and 7,respectively. Preferably, such contours are achieved by constraining theelongate shaft in a shaping fixture while heating the shaft 16 until itassumes the intended contour (e.g., by “heat setting” the shaft 16).

The guide catheter shaft structure as described above may be used toform a unitary guide lumen as shown in FIG. 1, or may be used to form aguide lumen segment that is coupled to the other guide lumen segments asshown in FIG. 3. The multiple guide lumen segments may have varyingflexion characteristics, different material characteristics (such asdifferent fillers for controlling the radio-opaqueness and/orechogenicity of the segments), and different shapes. Moreover, thereinforcing braid of the guide catheter shaft structure as describedabove may be omitted to provide for greater flexibility.

Advantageously, the guide catheter shaft (or shaft segment) of thepresent invention has lower material costs because the PEBAX®-basedshrink tubing has a lower cost than the fluorinated ethylene-propylene(FEP) shrink tubing typically used in the prior art devices. Themanufacturing process is also simplified because the process and toolingthat removes the FEP shrink tubing (or other type shrink tubing) can beavoided. Finally, where PEBAX® is used in commercially-availableproducts, it is likely that regulatory resubmission of the device can beavoided.

There has been described and illustrated herein an embodiment of animproved guide catheter (and improved guide catheter shaft) that employsa flexible intermediate sheath formed from a melt-processible firstpolyether-block amide material along with an outer sheath formed from adifferent second polyether-block amide material. The firstpolyether-block amide material has a melt temperature in the shrinktemperature range of the second polyether-block amide material. Whileparticular embodiments of the invention have been described, it is notintended that the invention be limited thereto, as it is intended thatthe invention be as broad in scope as the art will allow and that thespecification be read likewise. Thus, while particular geometries anddimensions of the assembly elements have been disclosed, it will beunderstood that other geometries and dimensions can be used. Moreover,while particular configurations and materials have been disclosed, itwill be appreciated that other configurations and materials could beused as well. It will therefore be appreciated by those skilled in theart that yet other modifications could be made to the provided inventionwithout deviating from its spirit and scope as claimed.

1. A guide catheter comprising: a hollow elongate shaft defining achannel, at least a portion of said elongate shaft including i) an innertube; and ii) a multilayer sheath formed around said inner tube, saidmultilayer sheath including an intermediate layer comprising amelt-processible first polyether-block amide material and an outer layercomprising a second polyether-block amide material different from saidfirst polyether-block amide material.
 2. A guide catheter according toclaim 1, wherein: said second polyether-block amide material has ashrink temperature range greater than a melt temperature range for saidfirst polyether-block amide material.
 3. A guide catheter according toclaim 2, wherein: said second polyether-block amide material comprises across-linked polyether-block amide material.
 4. A guide catheteraccording to claim 1, wherein: said first and second polyether-blockamide material comprise PEBAX®.
 5. A guide catheter according to claim1, wherein: said multilayer sheath further comprises reinforcingmaterial.
 6. A guide catheter according to claim 5, wherein: saidreinforcing material comprises a braid of reinforcing filaments aroundsaid inner tube.
 7. A guide catheter according to claim 6, wherein: saidreinforcing filaments comprise one of a metallic material and plasticmaterial.
 8. A guide catheter according to claim 6, wherein: saidreinforcing filaments comprise a radio-opaque material.
 9. A guidecatheter according to claim 6, wherein: said reinforcing filamentscomprise an echogenic material.
 10. A guide catheter according to claim1, wherein: said inner tube is formed from a synthetic polymericmaterial.
 11. A guide catheter according to claim 10, wherein: saidsynthetic polymeric material is lubricious.
 12. A guide catheteraccording to claim 11, wherein: said synthetic polymeric materialcomprises one of PTFE and polyethylene.
 13. A guide catheter accordingto claim 1, further comprising: said elongate shaft has a proximal enddisposed opposite a distal end, and a fitting affixed to said proximalend.
 14. A guide catheter according to claim 13, further comprising: ahandle affixed to said proximal end.
 15. A guide catheter according toclaim 13, further comprising: a reduced diameter distal tip affixed tosaid distal end.
 16. A guide catheter according to claim 1, wherein:said elongate shaft comprises multiple segments that are joinedtogether.
 17. A guide catheter according to claim 1, wherein: a portionof said elongate shaft has one of a straight shape and bent shape.
 18. Aguide catheter according to claim 17, wherein: said bent shape comprisesone of a curve, hook, and compound curve.
 19. A guide catheter shaftcomprising: i) an inner tube defining a channel; and ii) a multilayersheath formed on said inner tube, said multilayer sheath including anintermediate layer comprising a melt-processible first polyether-blockamide material and an outer layer comprising a second polyether-blockamide material different from said first polyether-block amide material.20. A guide catheter shaft according to claim 19, wherein: said secondpolyether-block amide material has a shrink temperature range greaterthan a melt-temperature range for said first polyether-block amidematerial.
 21. A guide catheter shaft according to claim 20, wherein:said second polyether-block amide material comprises a cross-linkedpolyether-block amide material.
 22. A guide catheter shaft according toclaim 19, wherein: said first and second polyether-block amide materialcomprise PEBAX®.
 23. A guide catheter shaft according to claim 19,wherein: said multilayer sheath further comprises reinforcing material.24. A guide catheter shaft according to claim 23, wherein: saidreinforcing material comprises a braid of reinforcing filaments aroundsaid inner tube.
 25. A guide catheter shaft according to claim 19,wherein: said inner tube is formed from a synthetic polymeric material.26. A guide catheter shaft according to claim 25, wherein: saidsynthetic polymeric material is lubricious.
 27. A method of forming aguide catheter shaft, comprising: forming an inner tube structure;forming an intermediate sheath around the inner tube structure, theintermediate sheath comprising a melt-processible first polyether-blockamide material; applying a shrink tube layer around the intermediatesheath, said shrink tube layer comprising a second polyether-block amidematerial that has a shrink temperature range greater than a melttemperature range of said first polyether-block amide material; andheating the resulting structure at a temperature within the shrinktemperature range of the shrink tube layer, thereby causing the secondpolyether-block amide material to shrink and the first polyether-blockamide material to melt, and bonding the multilayer sheath to the innertube structure.
 28. A method according to claim 27, further comprising:applying reinforcing material around the inner tube structure such thatit is disposed between the inner tube structure and the intermediatesheath.
 29. A method according to claim 27, wherein: said secondpolyether-block amide material comprises a cross-linked polyether-blockamide material.
 30. A method according to claim 27, wherein: said firstand second polyether-block amide material comprise PEBAX®.
 31. A methodaccording to claim 27, wherein: said inner tube structure is formed froma synthetic polymeric material.
 32. A method according to claim 31,wherein: said inner tube structure is formed by coating a mandrel with asynthetic polymeric material and then extruding the coated mandrelthrough a die.
 33. A method according to claim 31, wherein: saidsynthetic polymeric material is lubricous.
 34. A method according toclaim 32, wherein: said synthetic polymeric material comprises one ofPTFE and polyethylene.
 35. A method according to claim 27, wherein: saidreinforcing material is applied around said inner tube structure bybraiding reinforcing filaments about said inner tube structure.
 36. Amethod according to claim 35, wherein: said reinforcing filamentscomprise one of a metallic material and plastic material.
 37. A methodaccording to claim 35, wherein: said reinforcing filaments comprise aradio-opaque material.
 38. A method according to claim 34, wherein: saidreinforcing filaments comprise an echogenic material.
 39. A methodaccording to claim 27, wherein: a portion of said guide catheter shaftis formed to have one of a straight shape and a bent shape.
 40. A methodaccording to claim 39, wherein: said bent shape comprises one of acurve, hook, and compound curve.